1. Field of the Invention
The present invention relates to a method and an apparatus for removing an image forming substance from the surface of an image holding member on which an image constructed by the image forming substance is formed by an image forming apparatus such as a copying machine, a facsimile telegraph, a printer, etc. More particularly, the present invention relates to a method and an apparatus for removing an image forming substance from an image holding member in which the image forming substance on the image holding member is heated to be melted or softened, and a separating member having adhesive force stronger than that between the image holding member and the image forming substance comes in contact with the image forming substance, and the image forming substance is separated and removed from the image holding member when the separating member and the image holding member are separated from each other.
2. Description of the Related Art
There are generally various kinds of known methods and apparatuses for removing an image forming substance such as toner from a recorded image holding member such as a sheet of paper. For example, Japanese Patent Application Laying Open (KOKAI) No. 1-101576 shows an image forming substance removing method using a solvent. In this image forming substance removing method, a sheet of paper attaching toner thereto is dipped into a soluble solvent of toner resin and a supersonic wave is vibrated to separate the toner dissolved into the solvent from a paper face. Further, Japanese Patent Application Laying Open (KOKAI) No. 4-300395 shows another image forming substance removing method in which a solvent is attached to a printed portion of used paper by an attaching method using dipping, spraying or coating, etc., to dissolve toner so that the dissolved toner is removed from the printed portion by a removing method such as cleaning, air suction, adsorbent contact, mechanical separation, electrostatic adsorption, etc.
For example, Japanese Patent Application Laying Open (KOKAI) No. 2-55195 shows another image forming substance removing method in which no solvent is used. In this image forming substance removing method, thermally melted ink or toner is attached by an electrophotographic system or a thermal transfer system onto a printed member in which a supporting member is coated with a mold-releasing agent. An ink separating member is overlapped with the printed member and is moved between a heating roller and a pressure roller. After the ink separating member is cooled, the ink is attached to the ink separating member by separating the ink separating member from the printed member so that the ink is removed from the printed member. Further, Japanese Patent Application Laying Open (KOKAI) No. 4-64472 shows an eraser having at least an endless sheet, heating and cooling rollers, a pressing roller and a driving section. The endless sheet has thermally melted resin on a surface thereof. The heating and cooling rollers support and rotate the endless sheet. The pressing roller presses a sheet of erasable paper having a mold-released surface against softened or thermally melted resin. The driving section operates these rollers in association with each other. Further, Japanese Patent Application Laying Open (KOKAI) No. 4-82983 shows an image forming substance removing apparatus having two parallel rollers, a heater, a scraper and a separator. The two parallel rollers are arranged in parallel with each other and come in press contact with each other and are rotated such that a sheet of paper passes through a press contact portion of these two parallel rollers. The heater heats at least one of the two parallel rollers. The scraper separates the paper sheet passing through the press contact portion from these two parallel rollers. The separator removes an image forming substance attached onto each of the two parallel rollers therefrom.
The above removing method and apparatus using no solvent can be used to remove the image forming substance from the recorded image holding member recording an image on a sheet of normal paper having exposed paper fibers on a surface thereof. In this case, for example, the image forming substance having thermally melted resin as a principal component is melted and attached onto the image holding member in a fixing process of the electrophotographic system. Accordingly, the image forming substance is strongly fixed onto paper fibers on the image holding member surface. Therefore, when the image forming substance is removed from the paper fibers, paper fibers on this image holding member surface are separated therefrom together with the image forming substance so that the paper sheet is damaged and a paper quality is reduced. In particular, when the above ink separating member, the endless sheet or each of the above rollers is heated or pressurized to improve a removing property of the image forming substance, fixing force between the image forming substance and the image holding member is reversely increased in various kinds of conditions so that it is difficult to remove the image forming substance from the image holding member.
Therefore, inventors of this patent application proposed another image forming substance removing method in Japanese Patent Application No. 4-255916. In this image forming substance removing method, at least one kind of water or aqueous solution is selected from a group of water as an unstabilizing agent, an aqueous solution including a surfactant, an aqueous solution including a water-soluble polymer, and an aqueous solution including a surfactant and a water-soluble polymer. This selected water or aqueous solution is held in a recorded image holding member. An image forming substance on the image holding member is heated to be melted or softened. A separating member having adhesive force stronger than that between the image holding member and the image forming substance then comes in contact with the image forming substance. When the separating member is separated from the image holding member, the image forming substance is separated and removed from the image holding member. In accordance with this image forming substance removing method, only the image forming substance can be removed from the image holding member without relatively reducing a paper quality of the image holding member.
FIG. 1 shows one constructional example of a toner separating unit of a toner removing apparatus capable of realizing this removing method. The toner separating unit separates toner as the image forming substance from a sheet of transfer paper 10 as the image holding member.
This toner separating unit has a plurality of supporting rollers 41, 42, a belt 44 for a toner offset, upper and lower heating rollers 45, 46, a tension roller 49 and a rotating brush roller 50. The belt 44 for a toner offset is arranged as a separating member having a belt shape and wound around a separating roller 43. The upper and lower heating rollers 45 and 46 respectively have heating lamps 45a and 46a therein and are arranged such that these heating rollers 45 and 46 come in press contact with each other by a biasing means 45b such as a spring through the belt 44. The tension roller 49 is biased by a biasing means 49a such as a spring such that a belt portion between the supporting rollers 41 and 42 is pressed inside. The rotating brush roller 50 removes toner from a surface of the belt 44. At least a surface of this belt 44 is formed by a material having adhesive force stronger than that between a surface of the transfer paper sheet 10 and softened or melted toner. In this toner removing apparatus, after a belt portion passes through a pressurizing portion between the upper and lower heating rollers 45 and 46, a moving direction of the belt 44 is rapidly changed around the separating roller 43 winding this belt portion therearound. Thus, the transfer paper sheet 10 is separated from the belt 44 by using curvature. In this separation, the toner is separated and removed from the surface of the transfer paper sheet 10.
In the image forming substance removing apparatus for removing the image forming substance from the image holding member and proposed in the above Japanese Patent Application No. 4-255916, etc., there is a case in which the image holding member is cooled and solidified until the image holding member is separated from a surface of the separating member after the separating member comes in contact with the image forming substance softened or melted on the image holding member. For example, in the constructional example of the toner removing apparatus shown in FIG. 1, there is a case in which toner heated by the upper and lower heating rollers 45 and 46 and softened or melted on the transfer paper sheet 10 is cooled and solidified until a separating position of the transfer paper sheet 10 separated by the separating roller 43. When the image forming substance such as toner, etc. is cooled and solidified, no image forming substance can be reliably separated and removed from the image holding member even when the separating member is separated from the image holding member in this cooled and solidified state. This is because no adhesive force between the image forming substance and the image holding member is smaller than adhesive force between the image forming substance and the separating member surface in many cases. The image forming substance is also insufficiently separated from the image holding member when the above unstabilizing agent is not provided to the image holding member.